This application pertains to the art of pivotal connectors and more particularly to electrical fixture swivels. The invention is particularly applicable to lamp swivels for use in conjunction with swivel lamps and will be described with particular reference thereto. However, it will be appreciated that the invention is applicable to other pivotal connections and joints. The invention may find utility in pivotally connecting fluid carrying pipes or tubes, structural rods or bars, and the like.
Swivels for lamps and other electrical fixtures commonly include a male and a female swivel member. The male and female members have matching engaging surfaces on which they slide as they rotate relative to each other about a central axis. Adjacent its bearing surface, the male member has an extending annular flange. Adjacent its engaging surface, the female member has an annular collar. To connect the male and female members, a press flares the flange of the male member around the collar of the female member. The amount of pressure applied by the press determines the degree of frictional engagement between the engaging surfaces. This, in turn, determines the frictional drag or resistance to relative rotational movement of the male and female members. The male and female members are each connected outward extending arms. One of the arms is commonly connected with a base or mounting unit and the other arm is commonly connected with a fixture for holding a lamp or the like. The swivel allows the position of the lamp to be changed or moved to suit the lighting requirements of the user.
Various problems have been encountered with this type of swivel. One problem is controlling the amount of frictional drag between the male and female members. The amount of frictional drag is determined by the amount of force exerted by the press in the flaring operation. Small tolerances, on the order of a thousandth of an inch, in the flaring operation mark the difference between a swivel which is loose and sloppy and a swivel which is stiff and difficult to turn. It is desirable that swivel lamps require generally the same amount of force to rotate the lamp regardless of the length of the arms. A longer lamp or lever arm tends to decrease the force required to rotate the lamp. Thus, to standardize the force for rotating the lamp, the optimal frictional drag must be varied in accordance with the length of the lamp arm. This commonly necessitates that the swivels and arms be sold in matched sets. Further, the amount of drag tends to be altered in the finishing or plating operation and with use.
Another problem with the prior art swivels resides in the difficulty encountered in threading electrical wires through the arms and the swivel. To prevent damage of the wire, the arms are soldered or braised into the swivel and the flaring operation is performed before the arms and swivel are wired. Once the arms and swivel are assembled, they present a tortuous path along which the wire must be threaded. This renders wiring an arduous and labor intensive operation.
Yet another problem with the prior art swivels is the relatively high plating defect rate. After the swivel members are flared together and the arms are soldered or braised to the swivel, the arms and swivel are commonly plated to improve their esthetic appeal. In the plating operation, the arms and swivel assembly are first cleaned or etched by dipping in an acid solution. Following the acid bath, the assembly is dried and plated. The acid solution tends to become trapped between the engaging surfaces and between the collar and flange of the swivel members. After the assembly has been plated, any trapped acid solution tends to leak out onto the plated surface discoloring or dissolving the plating.
Others have suggested connecting swivel members together with threaded elements. However, when one of the swivel members rotates relative to one of the threaded elements, there is a tendency for the threaded elements to loosen.
The present invention overcomes the above-referenced problems and others yet provides a swivel which is simple and inexpensive to fabricate and install.